The Bolivia summit comes after a preparatory meeting between representatives from the world's leading economies in Washington ahead of the December UN summit in Cancun, Mexico.

The US-led Major Economies Forum comprises 17 countries responsible for the bulk of global emissions, but excludes smaller and poorer nations.

Morales is planning to propose a world referendum this week to ask up to two billion people how they think governments should tackle climate change, and organisers plan to take the final text drafted at the summit to Cancun.

The end of the summit is planned to coincide with Earth Day which is marked throughout most of the world on Thursday, April 22.